1. Field of the Invention
The present invention relates to an apparatus and method for adaptive camera control. More particularly, the present invention relates to an apparatus and method for adaptive camera control to stabilize an image according to a predicted trajectory.
2. Description of the Related Art
Mobile terminals are developed to provide wireless communication between users. As technology has advanced, mobile terminals now provide many additional features beyond simple telephone conversation. For example, mobile terminals are now able to provide additional functions such as an alarm, a Short Messaging Service (SMS), a Multimedia Message Service (MMS), E-mail, games, remote control of short range communication, an image capturing function using a mounted digital camera, a multimedia function for providing audio and video content, a scheduling function, and many more. With the plurality of features now provided, a mobile terminal has effectively become a necessity of daily life.
Many mobile terminals now offer a video-recording feature using a built-in camera. However, because the mobile terminals are typically hand-held, the resulting video tends to be jerky or blurry due to the movement of the user's hands while recording. In many cases, either interesting information is lost or not enough information is captured for post-processing to compensate for this motion. The techniques for addressing this issue are referred to as image stabilization.
Image stabilization techniques typically fall into two categories: optical stabilization and digital stabilization. In optical stabilization, the lens or the image sensor is moved to counter the movement of the camera. Since this requires a physical element to move the lens or the image sensor, optical stabilization is generally found on higher-end or expensive cameras.
Digital image stabilization shifts the image in post-processing to counter the movement of the camera when the video was captured. Digital image stabilization employs pixels outside the border of the visible frame to provide a buffer for the motion. This technique reduces distracting vibrations from videos or improves still image quality by allowing the user to increase the exposure time without blurring the image. This technique does not affect the noise level of the image, except in the extreme borders when the image is extrapolated.
On most cameras, no extra pixels are captured outside of the border of the visible frame. As a result, frames have to be cropped to remove uneven borders in order to align frames. Moreover, cameras typically capture frames at a fixed frame rate without respect to the motion of the camera. When the camera moves, the slow frame rate may cause the loss of interesting information.
Another issue with consumer cameras commonly seen on mobile devices is the real-time response. The camera settings may require a relatively long time to take effect. Moreover, the motion information extracted from consecutive image frames is very limited. For example, the motion information normally has no concept of acceleration and trajectory. Due to the limited information provided by “motion vectors”, the effectiveness of the image stabilization is limited.
Accordingly, there is a need for an apparatus and method for providing improved digital image stabilization.